I'm not sure of the context you are talking about, but if you are trying to move a value point to a different time, then you can only move it between to two adjacent points. So if you had a point at 5 seconds, another at 10, and another at 15, you can move the point at 10 between 5 and 15. Check to make sure there are not multiple points at the same time. That would restrict the range.